The impact of peak-and-valley operation on the electrolyzer

This topic has been discussed many times before; peak-and-valley power operation is not widely used in China. As for me, since I started working with caustic soda, I have never heard of any company adopting this approach. The reasons are mainly that operating at high loads reduces various costs (generally referring to financial benefits, equipment depreciation, and other factors). Another important factor is related to equipment issues – whether the equipment’s performance is reliable and advanced is a concern, and automatic tracking and adjustment mechanisms also present problems. Thirdly, frequent changes in current levels place high demands on the operators, and repeated operations inevitably lead to mistakes and other issues. Fourth, the stable operation of the system without any accidents is also the greatest benefit for a company. Therefore, the long-term stable operation of the system is beneficial for enterprises. Of course, given the current downturn in the chlor-alkali industry, it is necessary to operate on a peak-valley basis. This is also a good practice; in Japan, there is a significant difference between electricity prices during the day and at night, and Japanese companies usually operate their systems according to peak and off-peak electricity rates. When changing the operating current load, as long as the operating conditions are controlled in accordance with the instructions provided by the manufacturers of the ion exchange membrane and the electrolyzer, it will not cause any damage to either the electrolyzer or the ion exchange membrane; this approach is feasible.

Our company has been using this system for the past two years, and to be honest, I’ve always been against it. Every day, peak-and-valley operations are carried out, which affects the equipment, increases the amount of work required, and makes the performance metrics less stable. On average, we have to shut down the equipment more than 30 times a year, and there are 3 or 4 cases of human error as well. It’s impossible to achieve zero operations and zero errors when carrying out such operations on a daily basis; people inevitably make mistakes, especially since peak-demand periods usually occur around 11 p.m. If this problem could be solved, electricity costs would definitely be reduced. Of course, you can give it a try; in our case, the extent of peak-shaving required is also very large

This method is feasible. As long as the relevant parameters are adjusted accordingly when the load is changed, it has no impact on either the electrolyzer or the ion exchange membrane.

Operation with peak-valley electricity: I’ve discussed this with Asahi Kasei’s staff, and as long as it is kept within specified limits, there should theoretically be no issues. However, the level of expertise, control methods, and online monitoring available in China are not yet sufficient, so it’s better to maintain a stable current level.

Our company also operated it in the past; once the current returned to normal levels, we noticed that power consumption started to rise sharply

It’s feasible; the operation isn’t an issue – the mindset is the problem. Employees all want to earn more while working less; if a company doesn’t make profits, how can its employees get more?

I am against frequent fluctuations in current levels; a stable production load is more important than anything else

This is what we have been doing all along, mainly to reduce costs. We need to start by considering efficiency, as this will also have an impact on the electrolyzers; it’s impossible to avoid some minor issues in operation

As long as there is a steady rise and fall, and the flow rate of saline and the gas phase are adjusted in accordance with the requirements, load adjustment to avoid peak periods has little impact on the electrolyzer； However, it is important to analyze and check the voltage withstand rating of the rectifier transformer oil on schedule, in order to avoid failures during adjustment.

This method is feasible; we have been using it, making adjustments 4 times a day. As long as the operations are carried out properly, interlocks or other abnormalities generally do not occur. However, it does have an impact on the increase in slot voltage, with the rate of increase being faster than before (50-60 KWH/year).